2.
Now you see GarageBandExtraContent.pkg, also double click it.
Installer will launch, continue and continue, finish the installer.

3.
Open the garageband, you’ll see the updated apple loops and instruments.

Kale R. method: Thank you! You sir, are a gentlemen and a scholar. However, I had to take the necessary steps that differed from your instructions (to help avoid confusion for other readers, as I know this is a widespread problem).1. I found the .TAR file (GarageBandExtraContent.tar) in the trash.
2. I dragged the .TAR file to the desktop
3. I unarchived it and a new folder appeared on my desktop.
4. In the folder, there was another .TAR file (GarageBandExtraContent.pkg.tar) and an unknown file with no file extension. It was called signature.
5. I unarchived the new .TAR file and in the new folder was the .PKG file (GarageBandExtraContent.pkg) you mentioned.
6. I followed the onscreen instructions and opened GarageBand.

The missing instruments and loops were installed and functional! Thanks again for the help, coolchiselz!

that’s not necessary. there are two ways to delete anything from an audio file in GB.

One is in the standard Tracks display.. let the audio play up to the element to be deleted, and press the space bar. this will stop the playback and the ‘playhead’ right at that spot. Edit>split track. Press space to play, and at the end of the element to be deleted, press spacebar again to stop. Again do edit>split track.

You have split the audio into three regions: keep|delete|keep .. you need to click in the blank space BELOW the track to deselect the track, then click on the region-to-delete. Press the Delete key on the keyboard. This leaves a hole in your sound track.. click on the rightmost region and drag it to the left, across the space, right up against the leftmost ‘keep’ region.

SAVE YOUR WORK.. CMD-S.

There is another way to do it with the Edit Region icon, but you’ll have to use GB’s Help command for that one.